Carochi was born in Florence. He went to Rome where he entered the Society of Jesus. From Rome he went to the New World, arriving in New Spain (now Mexico). There he dedicated himself to the study of the indigenous languages, and became proficient in Nahuatl and Otomi. He was a friend of the Bishop and later Viceroy of New Spain, Juan de Palafox y Mendoza, as is documented by the letters existing today written by Carochi to the bishop.
Carochi had an acute understanding of the Nahuatl language and was the first grammarian to understand and propose a consistent transcription of two difficult phenomena in Nahuatl phonology, namely vowel length and the saltillo. His Arte or grammar was seen as important soon after its publication, and as early as 1759 a version edited by Ignacio Paredes was issued. This version however lacks most of the virtues of the original work.
Today his original Arte de la lengua Mexicana is considered by linguists to be the finest and most useful of the extant early grammars of Nahuatl. He also wrote a grammar of the Otomi language, which is now lost.
Of the works of Carochi only the Arte de la lengua Mexicana has been printed; the others exist only in manuscript form.
- Arte de la Lengua mexicana con la declaración de todos sus adverbios, printed in Mexico in 1645
- Vocabulario copioso de la Lengua mexicana
- Gramática de la Lengua Otomí
- Vocabulario Otomí
- Sermones en Lengua mexicana
- Bandelier, Adolph Francis (1908). "Horacio Carochi". Catholic Encyclopedia. vol. III (New Advent online reproduction ed.). New York: Robert Appleton and Company. OCLC 1017058. Retrieved 2008-05-13.
- Bustamante, Jesús (1995). "Professional Indian, Professional Criollo. Nahuatl Versions of Classical Spanish Theatre". In Henriette Bugge and Joan Pau Rubiés (eds.). Shifting Cultures: Interaction and Discourse in the Expansion of Europe. Periplus Parerga, Bd. 4. Münster, Germany: LIT Verlag. pp. 71–96. ISBN 3-8258-2614-7. OCLC 36278908.